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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COLOPHON |
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PERF-INJECT(1) perf Manual PERF-INJECT(1)
perf-inject - Filter to augment the events stream with additional
information
perf inject <options>
perf-inject reads a perf-record event stream and repipes it to
stdout. At any point the processing code can inject other events
into the event stream - in this case build-ids (-b option) are
read and injected as needed into the event stream.
Build-ids are just the first user of perf-inject - potentially
anything that needs userspace processing to augment the events
stream with additional information could make use of this
facility.
-b, --build-ids
Inject build-ids of DSOs hit by samples into the output
stream. This means it needs to process all SAMPLE records to
find the DSOs.
--buildid-all
Inject build-ids of all DSOs into the output stream regardless
of hits and skip SAMPLE processing.
--known-build-ids=
Override build-ids to inject using these comma-separated pairs
of build-id and path. Understands file://filename to read
these pairs from a file, which can be generated with perf
buildid-list.
-v, --verbose
Be more verbose.
-i, --input=
Input file name. (default: stdin)
-o, --output=
Output file name. (default: stdout)
-s, --sched-stat
Merge sched_stat and sched_switch for getting events where and
how long tasks slept. sched_switch contains a callchain where
a task slept and sched_stat contains a timeslice how long a
task slept.
-k, --vmlinux=<file>
vmlinux pathname
--ignore-vmlinux
Ignore vmlinux files.
--kallsyms=<file>
kallsyms pathname
--itrace
Decode Instruction Tracing data, replacing it with synthesized
events. Options are:
i synthesize instructions events
y synthesize cycles events
b synthesize branches events
c synthesize branches events (calls only)
r synthesize branches events (returns only)
x synthesize transactions events
w synthesize ptwrite events
p synthesize power events (incl. PSB events for Intel PT)
o synthesize other events recorded due to the use
of aux-output (refer to perf record)
I synthesize interrupt or similar (asynchronous) events
(e.g. Intel PT Event Trace)
e synthesize error events
d create a debug log
f synthesize first level cache events
m synthesize last level cache events
M synthesize memory events
t synthesize TLB events
a synthesize remote access events
g synthesize a call chain (use with i or x)
G synthesize a call chain on existing event records
l synthesize last branch entries (use with i or x)
L synthesize last branch entries on existing event records
s skip initial number of events
q quicker (less detailed) decoding
A approximate IPC
Z prefer to ignore timestamps (so-called "timeless" decoding)
T use the timestamp trace as kernel time
The default is all events i.e. the same as --itrace=iybxwpe,
except for perf script where it is --itrace=ce
In addition, the period (default 100000, except for perf script where it is 1)
for instructions events can be specified in units of:
i instructions
t ticks
ms milliseconds
us microseconds
ns nanoseconds (default)
Also the call chain size (default 16, max. 1024) for instructions or
transactions events can be specified.
Also the number of last branch entries (default 64, max. 1024) for
instructions or transactions events can be specified.
Similar to options g and l, size may also be specified for options G and L.
On x86, note that G and L work poorly when data has been recorded with
large PEBS. Refer linkperf:perf-intel-pt[1] man page for details.
It is also possible to skip events generated (instructions, branches, transactions,
ptwrite, power) at the beginning. This is useful to ignore initialization code.
--itrace=i0nss1000000
skips the first million instructions.
The 'e' option may be followed by flags which affect what errors will or
will not be reported. Each flag must be preceded by either '+' or '-'.
The flags are:
o overflow
l trace data lost
If supported, the 'd' option may be followed by flags which affect what
debug messages will or will not be logged. Each flag must be preceded
by either '+' or '-'. The flags are:
a all perf events
e output only on errors (size configurable - see linkperf:perf-config[1])
o output to stdout
If supported, the 'q' option may be repeated to increase the effect.
--strip
Use with --itrace to strip out non-synthesized events.
-j, --jit
Process jitdump files by injecting the mmap records
corresponding to jitted functions. This option also generates
the ELF images for each jitted function found in the jitdumps
files captured in the input perf.data file. Use this option if
you are monitoring environment using JIT runtimes, such as
Java, DART or V8.
-f, --force
Don’t complain, do it.
--vm-time-correlation[=OPTIONS]
Some architectures may capture AUX area data which contains
timestamps affected by virtualization. This option will update
those timestamps in place, to correlate with host timestamps.
The in-place update means that an output file is not
specified, and instead the input file is modified. The options
are architecture specific, except that they may start with
"dry-run" which will cause the file to be processed but
without updating it. Currently this option is supported only
by Intel PT, refer perf-intel-pt(1)
--guest-data=<path>,<pid>[,<time offset>[,<time scale>]]
Insert events from a perf.data file recorded in a virtual
machine at the same time as the input perf.data file was
recorded on the host. The Process ID (PID) of the QEMU
hypervisor process must be provided, and the time offset and
time scale (multiplier) will likely be needed to convert guest
time stamps into host time stamps. For example, for x86 the
TSC Offset and Multiplier could be provided for a virtual
machine using Linux command line option no-kvmclock. Currently
only mmap, mmap2, comm, task, context_switch, ksymbol, and
text_poke events are inserted, as well as build ID
information. The QEMU option -name debug-threads=on is needed
so that thread names can be used to determine which thread is
running which VCPU. Note libvirt seems to use this by default.
When using perf record in the guest, option
--sample-identifier should be used, and also --buildid-all and
--switch-events may be useful.
--guestmount=<path>
Guest OS root file system mount directory. Users mount guest
OS root directories under <path> by a specific filesystem
access method, typically, sshfs. For example, start 2 guest
OS, one’s pid is 8888 and the other’s is 9999:
$ mkdir ~/guestmount
$ cd ~/guestmount
$ sshfs -o allow_other,direct_io -p 5551 localhost:/ 8888/
$ sshfs -o allow_other,direct_io -p 5552 localhost:/ 9999/
$ perf inject --guestmount=~/guestmount
perf-record(1), perf-report(1), perf-archive(1), perf-intel-pt(1)
This page is part of the perf (Performance analysis tools for
Linux (in Linux source tree)) project. Information about the
project can be found at
⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩. If you have a
bug report for this manual page, send it to
[email protected]. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩
on 2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-10.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to [email protected]
perf 2022-10-04 PERF-INJECT(1)
Pages that refer to this page: perf(1), perf-arm-spe(1), perf-intel-pt(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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